As Internet protocol (IP) becomes the transport layer of choice, operators are faced with significant challenges to provide accurate and relevant measurement of IP network performance. Tools are available such as ICMP Ping/TraceRoute and UDP Echo, but these provide limited value in the context of performance as they typically lack precision, accuracy or relevancy for assuring carrier-grade performance. Other tools exist that leverage the TCP/IP suite but lack the broad acceptance of the network equipment manufacturer community that is required for seamless operation in cross-network/ multi-vendor environments.

To expand their networks to other hard-to-reach locations, wireless providers are turning to the deployment of alternative infrastructures, such as fiber-to-the-antenna (FTTA), remote radio heads (RRH), and other small-cell alternatives, most of which are fiber-based.

This application note provides an overview of the basic concepts of PMD and the impact that strong-mode and weakmode coupling have on PMD testing; the accuracy of test instruments will also be discussed.